Zimbabwe's government has threatened to jail anyone who disrespects the national flag or sells it without permission, enraging activists who have used the banner as a rallying point for mass protests.

The state has been struggling to contain months of demonstrations against financial chaos and corruption, many of which have been organized by the online #ThisFlag campaign.

Protesters have regularly waved the green-yellow-and-red flag and marched with it draped around their shoulders, answering Pastor Evan Mawarire's call in an online video to take pride in their flag and the ideals it embodies.

"Members of the public who participate in any action or activity involving the national flag or to bring the national flag into disrepute are warned that they are liable to prosecution," Virginia Mabiza, a senior official in the Justice Ministry, said in a statement released late Tuesday.

The government will make use of an existing law that bans production and sale of the flag without the Justice Ministry's permission, she said.

Under the law, it is an offense to "burn, mutilate or otherwise insult the national flag," and anyone convicted of such a crime faces a $200 fine, up to six months in jail or both, the statement said.

Promise Mkwananzi, leader of the #Tajamuka movement, which has used social media to organize protests together with #ThisFlag, said his group would continue to use the flag.

"It is total insanity that government should ban citizens from using their own flag. We are going to continue to make use of our flag. It is our identity," Mkwananzi told Reuters.